The Port Authority’s light rail service resumed running early Monday before the morning rush hour. It was the first time trains had run past Wood Street since a derailment Friday night injured three people, sending one to the hospital.

Some riders on the North Shore Connector wound up making an unplanned walk through the tunnel Thursday morning. And while they were walking, other riders were waiting on T platforms wondering what was going on.

The Kenny Chesney-Tim McGraw concert at Heinz Field on Saturday proved to be a test for the Port Authority’s North Shore Connector. “It was larger than a sellout Pirates game type of event, so we were a little bit cautious going in,” Port Authority spokesman Jim Ritchie said.